Testing is done at the beginning and end of the exercise-training intervention period to determine what effect the intervention has had on the individual's blood pressure regulation. This testing consists of 2 sequential study days. During the first day's testing, which will last about 2 hours, the participant will receive 8 low doses of atropine to alter vagal effects. On the second day, which will take about 4 hours, the participant will receive sodium nitroprusside, phenylephrine, and low-dose atropine while sympathetic nervous activity is recorded. Differences in blood pressure regulation pre- and post-training will be studied.